2018-02-13 17:35 GMT+09:00 Arnd Bergmann <arnd@arndb.de>:> On Tue, Feb 13, 2018 at 2:53 AM, Randy Dunlap <rdunlap@infradead.org> wrote:>> On 02/12/2018 05:41 PM, Masahiro Yamada wrote:>>> 2018-02-13 8:48 GMT+09:00 Randy Dunlap <rdunlap@infradead.org>:>>>> On 02/12/2018 07:24 AM, Kees Cook wrote:>>>>> On Mon, Feb 12, 2018 at 6:39 AM, Masahiro Yamada>>>>> <yamada.masahiro@socionext.com> wrote:>>>>>>>>>>> (And in thinking about this, does Kconfig know the true $CC in use?>>>>>>> i.e. the configured cross compiler, etc?)>>>>>>>>>>>> I was thinking of removing CONFIG_CROSS_COMPILE.>>>>>>>>>>>> A user can dynamically change CROSS_COMPILE from>>>>>> "make menuconfig".>>>>>>>>>> Most builds I've seen implement cross compilers as an environment>>>>> variable during all "make" invocations.>>>>>>>> I agree. I think you would break a bunch of build bots if you remove that.>>>>>>>>> For clarification, I suggested to remove CONFIG_CROSS_COMPILE.>>>>>> The following code:>>> https://github.com/torvalds/linux/blob/v4.16-rc1/Makefile#L315>>> https://github.com/torvalds/linux/blob/v4.16-rc1/init/Kconfig#L58>>>>>> I hope build bots are not using this.>>>>>>>>> Passing CROSS_COMPILE via the command line, environment>>> is still supported.>>>> OK, I misunderstood. That one can go away IMO.>> Removing it will break the workflow for some people in a minor way> though. Could we have the top-level Makefile try to detect the> CROSS_COMPILE? Instead of just using CC=gcc as the default,> we could check for ${ARCH}!=`uname -m` and then see if $PATH> contains a ${ARCH}-linux-gcc, ${ARCH}-elf-gcc or ${ARCH}-gcc.>> it will need slightly more complexity to deal with architectures> that have different identifiers in linux and gcc, but I think it would> be a nice feature anyway.>> Arnd

Some architectures such as m68k, mips, etc.do this in their arch/*/Makefileby using $(call cc-cross-prefix, ...)

But, currently we do not do this globally.

It would be possible to do it, but it does not meanbackward-compatible with CONFIG_CROSS_COMPILE.